Device and method for the production of three-dimensional objects

ABSTRACT

A device and a process for producing three-dimensional objects is indicated. The device has a container ( 1 ) for a medium ( 2 ) and a three-dimensionally positionable dispenser ( 4 ) for release of a material ( 3 ), the addition of which to the medium ( 2 ) leads to the formation of solid structures, into the medium ( 2 ). Addition of the material ( 3 ) by moving the dispenser in XYZ direction on a platform ( 8 ) below the filling height of the first material ( 2 ) in the container ( 1 ) leads to the formation of three-dimensional objects.

[0001] The invention relates to a device and a process for theproduction of three-dimensional objects.

[0002] It is known to produce three-dimensional objects starting from aCAD model of the object layer by layer. In the known process ofstereolithography, monomers are polymerised in the presence ofphotoinitiators by laser radiation. However, only a limited number ofmonomer types are suitable as materials. In 3D printing technology,ink-jet technology is used in order to bind powder particles in theparticular layer at the points corresponding to the cross-section of theobject using adhesives. However, this technology, like stereolithographyas well, require after-treatment of the blanks produced.

[0003] In addition, supporting constructions are required for formingthree-dimensional objects having projections, protuberances and lowercavities, in order to prevent distortion or breaking of thethree-dimensional object.

[0004] A different technique for generating three-dimensional models isselective laser sintering. A pulverulent material is thus applied inlayers and the particular uppermost powder layer is illuminated using alaser beam at points corresponding to the cross-section of the model.The powder melts or sinters there due to the energy input of the laser.However, the thermal stress of the material is high, so that sensitivepolymers are destroyed. Incorporation of biological components, such asfor example cells or proteins, is not possible. The generation ofhydrogels is also not possible.

[0005] A process for forming three-dimensional models is known fromFrench 2 583 334. Therein, a photoinitiator is added to a monomer liquidand the monomer is cured by irradiation. Alternatively, a monomerreacting with a thermal initiator is added to a neutral liquid. However,the accuracy of the formation of the three-dimensional object and thenumber of useable materials is limited.

[0006] Thermoplastic polymers are melted in the technology of FusedDeposition Modelling (FDM). The liquid melt leaves the nozzles as astrand and constructs three-dimensional objects by cooling in air. Thisprocess is limited to thermoplastic polymers having a high meltviscosity. The range of the materials used successfully here hitherto islimited to acrylonitrile-butadiene-styrene copolymers andpolycaprolactone. The processing temperature thus exceeds 100° C.; thisprevents the incorporation of thermally sensitive additives into the 3Dobject produced.

[0007] The object of the invention is the provision of an improveddevice or an improved process for producing three-dimensional objects.

[0008] This object is achieved by a process according to claim 1, adevice according to claim 24 or a use according to claim 27.

[0009] Further developments of the invention are indicated in thesub-claims.

[0010] In the process of the invention, an outlet opening of athree-dimensionally movable dispenser is positioned in a first material(2)—the plot medium—and a second material (3) consisting of one or morecomponents, which leads to the formation of solid structures in contactwith the first material (2), is released into the first material (2) toform three-dimensional objects. The first material 2 is designated belowas medium or plot medium 2 and the second material 3 as material 3, inorder to be able to carry out better differentiation between first (2)and second (3) material.

[0011] The action of the medium (2) thus consists firstly in buoyancycompensation and in damping of the movement of the metered, still liquidmaterial (3).

[0012] The two effects are clearly shown in FIGS. 2 and 3.

[0013] In FIG. 2, the lack of buoyancy compensation leads to running ofthe three-dimensional lattice structure of the data record. On the otherhand, in FIG. 3, the lattice structure is well formed and the cavitystructure between the layers remains fully intact.

[0014] This technical change “plotting” (dispersing) of a material (3)in a medium (2) having corresponding Theological properties described inmore detail below, leads to a considerable expansion of the range ofuseable materials.

[0015] Firstly, the material(s) (3) having low viscosity can beconstructed to form complicated three-dimensional objects. Secondly, themedium (2) in reactive form may be included in the curing process of thematerial (3). Thus, chemical reactions may proceed, but alsoprecipitation and complex-formation reactions. The polarity of thematerial 2 varies depending on the polarity of the material (3) fromhydrophilic (for example water) to completely non-polar (for examplesilicone oil) in order to control the adhesion properties of the layersto one another.

[0016] A supporting construction may almost always be dispensed with inthe process described here for constructing three-dimensional objects.

[0017] A very important detail of the invention is based on thetemperature variability of the process. In conjunction with the largenumber of possible medium (2)/material (3) combinations, processingconditions can also be realised at room temperature.

[0018] Hence, pharmaceuticals or living, human cells may be incorporatedinto 3D structures.

[0019] In a further development of the process, gelatine solution orwater is used as medium (2) and silicone rubber as material (3).

[0020] In a further development of the process, water is used as medium(2) and a wet-curable silicone having acetoxysilane groups as material(3).

[0021] In a further development of the process, water, a polyol or asolution of polyfunctional amines is used as medium (2) and apolyurethane (prepolymer) having isocyanate groups as material (3).

[0022] In a further development of the process, an aqueous solution ofcalcium ions and thrombin is used as medium (2), an aqueous solution offibrinogen as material (3).

[0023] In a further development of the process, an aqueous solution ofcalcium ions and thrombin is used as medium (2), an aqueous solution offibrinogen with living human cells (for example fibroblasts) as material(3).

[0024] In a further development of the process, a solution of apolyelectrolyte is used as medium (2), a solution of multivalentcations, multivalent anions or a polyelectrolyte as material (3).

[0025] In a further development of the process, a solution of calciumions and/or of protonated chitosan and/or thrombin is used as medium (2)and a solution of Na alginate and/or fibrinogen as well as living humanor mammalian cells as material (3).

[0026] In a further development of the process, an aqueous solution of aprotein is used as medium (2) and a salt solution as material (3).

[0027] In a further development of the process, a reaction-delayingsubstance is added to the material and/or the medium. This guaranteesthat the added material adheres to previously cured or solidifiedmaterial.

[0028] Further features and advantages can be seen from the followingdescription of embodiments using the attached figures. Of these:

[0029]FIG. 1 shows a schematic representation of a device of oneembodiment of the invention;

[0030]FIG. 2 shows a cross-section through a plotted 3D object; plotmedium (2)=air, material (3)=PU prepolymer;

[0031]FIG. 3 shows a cross-section through a plotted 3D object; plotmedium (2)=water, material (3)=PU prepolymer.

[0032]FIG. 4 shows a schematic cross-sectional view of a furtherembodiment of the invention.

[0033] The principle of the invention is illustrated below.

[0034] The device shown in FIG. 1 has a container 1, a dispenser 4 and acontrol 6 for the dispenser 4. The device is also designated below as3D-plotter.

[0035] One or more platforms 8, on which the three-dimensional object orobjects are formed, are provided in the container 1. A medium 2, whichis also designated as plot medium, may be added to the container 1 to apredetermined filling height.

[0036] The dispenser 4 is attached to a stand not shown in FIG. 1 andcan be moved at least in three axes x, y, z like the milling head of acomputer-controlled milling machine. An at least three-axis,computer-NC-controlled milling tool, in which the milling head isreplaced by the dispenser, is used by way of example as dispenser 4. Thedispenser 4 consists of a nozzle element with material inlet and outletopening(s) 5. One or more exchangeable cartridges for one or morematerial component(s) (3) are connected to the material inletopening(s), wherein the material component(s) 3 are added to the medium2 to form three-dimensional objects. In order to allow the materialcomponent(s) 3 to enter the medium 2 controlled by the nozzle element,compressed air or a further suitable, dried inert gas (nitrogen, argon),depending on metered material 3, may be introduced into the cartridgesregulated via the pipes 7. The dispenser 4 can be moved in the threedirections above and below the container 1, such that the nozzle elementcan be positioned within the container 1 with its outlet opening 5 belowthe filling height of the medium 2.

[0037] The outlet opening 5 is designed as a single nozzle or as anozzle panel. The smallest internal diameters of the outlet opening 5are about 150 μm in commercially available nozzles for compressedair-operated dispenser systems.

[0038] A different possibility for metering the material 3—without usingcompressed air, or an inert gas—may be effected by a pump as connectionbetween cartridge and nozzle element, in which the material itself isconveyed by the pump from the cartridge to the nozzle element.

[0039] One modification of this possibility envisages integrating thefunction pump/valve/nozzle in the nozzle element by a mechatronicsolution.

[0040] The control 6 is designed so that it controls thethree-dimensional movement of the dispenser 4, and the release ofmaterial component(s) 3 from the dispenser. It is a computer-NC control,which may additionally be coupled to a CAD/CAM and/or image-processingsystem.

[0041] The medium 2, that is the plot medium, is a liquid, thixotropic,gel-like, pasty, solid, pulverulent material present as granules. Aco-reactive medium, which enters reactions with the materialcomponent(s) 3, for example anionic or cationic polyelectrolytes,polyelectrolyte salt mixtures or substances having co-reactivefunctional groups, may be used as plot medium. Alternatively,precipitation agents for the material component(s) 3 are present in theplot medium.

[0042] The material components 3, which are released from the dispenserinto the plot medium 2, are liquid, gel-like, pasty materials. Examplesof the material components 3 are oligomers and polymers which are liquidat room temperature, melts of oligomers and polymers (“hot melts”),reactive oligomers and polymers, monomers, gels, for exampleone-component or two-component silicon rubbers, pastes, for examplefilled oligomers and polymers with organic and inorganic fillers,plastisols, that is polymer powders dispersed in plasticisers,solutions, two-component systems with co-reactive components, forexample isocyanates/alcohols and dispersions.

[0043] The medium 2 and the material component(s) 3 may be selected sothat by metering the material component(s) 3 into the medium 2, thelatter is dissolved, bound, melted, cured or adhered by the materialcomponent(s) 3 or with it/them. Conversely, the material component(s) 3may be dissolved, bound, melted, cured or adhered by the medium 2 orwith it.

[0044] A medium 2 may be selected having a density which is the same orapproximately the same or somewhat smaller/larger than that of thematerial component(s) 3, in order to compensate bending of the structurein the case of projecting parts of the structure to be formed.Alternatively, due to a thixotropic, gel-like, pasty or pulverulentconsistency of the medium 2, bending and positional changes of thestructure to be formed may be prevented in the plot medium by the medium2 itself.

[0045] In each case, the addition of material component(s) 3 into themedium 2 leads directly to the formation of three-dimensional solidstructures. No additional auxiliaries, such as for example irradiation,are necessary.

[0046] First Embodiment

[0047] The description of a first embodiment of the invention follows.

[0048] A pneumatically operated dispenser 4 of the principle describedabove is provided with a cartridge and has as outlet opening 5 a needlehaving an internal diameter of about 250 μm. A metering valve isconnected to the pipes 7 via hoses to regulate the pressure within thecartridges. This reduces the compressed air introduced from 7 bar to thenecessary cartridge pressure depending on the material (3). In addition,the reducing valve may be completely closed by the control 6, in orderto start or to interrupt the metering process. In operation, thecontainer 1 is filled with water. A silicone resin, which can be curedusing water, is placed into the cartridge of the dispenser 4.Acetoxysilanes, which effect acid-catalysed silanol polycondensationduring hydrolysis in the presence of water, are present in the silicone.

[0049] The free needle end is positioned above the platform 8 at astarting position within predetermined dimensions of thethree-dimensional object to be formed, which are preset by a computermodel of the object, via the control 6. The silicone is then applied tothe platform 8 to form the first layer of the three-dimensional objectcorresponding to the predetermined dimensions at an operating pressureof about 0.8 bar and at room temperature. The needle of the dispenser ismoved parallel to the platform by the control 6 such that a moving ratein XY direction of about 11 to 12 m/h is set. The silicone thus curesdirectly after adding to the water.

[0050] The addition of material 3 onto the platform 8 into the medium 2takes place either portion-wise at individual points to form microdots(micro-drops) or continuously to form microstrands for gel-like or pastymaterials 3 and as a microjet for liquid materials 3.

[0051] After completing the first layer of the three-dimensional object,the dispenser needle is positioned in the Z direction shown in FIG. 1above the first layer by changing the position of the dispenser 4. Thesecond layer of the three-dimensional object is formed by a controlledmovement of the dispenser head and controlled addition of silicone.These steps are repeated so that the three-dimensional object isproduced by successive formation of layers. When metering microstrands,the strand must not necessarily be separated between the individuallayers. This facilitates the construction of the 3D object from a singlemicrostrand.

[0052] For example, backbone-like or scaffolding three-dimensionalobjects may be produced in this manner, by forming strands runningparallel to one another in a first direction within the first layer. Agap may thus be present between the strands of one plane. Strandsparallel to one another in a second direction are then formed during theformation of the second layer. A backbone of layers of strands is thenconstructed by repeating these steps.

[0053] Microdots may be formed next to one another, on one another orwith gaps. Spiral deposition of microdots or microstrands leads to theformation of tubes, the size of which lies in the millimetre tocentimetre range, having an internal diameter of about at least 100 μm.

[0054] If three-dimensional objects having large projections or cuts areformed, there may be distortion of the object in water due to gravity.To avoid this problem, the thixotropy of the silicone is adapted, forexample by liquefying the silicone during the production process bystirring, shaking or vibrations or by control of the silicone thixotropyby means of organic and inorganic nanofillers. Alternatively, instead ofwater, a medium having a density the same or similar, that is somewhatsmaller/larger than that of the silicone, is used. Consequently, forceswhich act on projections of the three-dimensional object due to gravity,are compensated by the buoyancy. A further possibility for preventingdistortions of the three-dimensional object, is the use of thixtropic orthermoreversible gels instead of water, such as for example industrialgelatine, in which the material flow of the metered material is thennegligible.

[0055] In a modification of the process described above, the silicone isreplaced during plotting by other resins, for example by exchanging thecartridges. This produces the possibility of changing materialproperties and colours within the three-dimensional object. For example,backbones may be formed from a material in this manner, into whichdenser layers of a different material are incorporated.

[0056] Second Embodiment

[0057] In a second embodiment, a dispenser 4 is used which has aheatable needle as outlet opening 5. A plastisol, that is a polymerpowder dispersed in one or more plasticisers, is provided as material ina cartridge on the dispenser 4. Water is provided in the container 1.The plastisol becomes gelled within the heated needle immediately beforerelease into the water. The plastisol is cooled in the water and thussolidified. In addition, the plastisol may also be gelled later in anoven in order to improve the structural properties of thethree-dimensional object.

[0058] PU prepolymers with isocyanate and hydroxyl groups are a furtherexample. They are situated in the cartridge 4 at room temperature orslightly cooled and are gelled by heating in the heated needle of theoutlet opening 5.

[0059] Other chemical reactions are also conceivable here, which lead tosolidification/gelling and can be started by a short thermal impulse.

[0060] Third Embodiment

[0061] In the third embodiment, a co-reactive system comprising severalmaterials is used. The dispenser 4 is provided with a cartridge and witha needle at the outlet opening 5. A polyurethane having functionalisocyanate groups is initially placed in the cartridge. The container 1is filled with water or an aqueous amine solution. During the additionof the polyurethane there is a reaction with the water or with theaqueous amine solution and curing of the co-reactive system.

[0062] In a modification of this embodiment, the dispenser 4 is providedwith two cartridges. A reactive resin is present in the one cartridgeand a component for curing the reactive resin is present in the othercartridge. When using mixing nozzles, the substances initially placed inthe cartridges are mixed with exclusion of air before or during additioninto a plot medium, such as for example water. The reactive resin andthe component for curing react with one another with formation of solidthree-dimensional structures.

[0063] Alternatively, co-reactive systems which lead to the formation ofsolid three-dimensional structures by boundary polycondensationreactions or by polyelectrolyte-complex formation, may be used in themanner shown above.

[0064] Fourth Embodiment

[0065] In a further embodiment, a medium 2, which reacts with thematerial 3 such that after removing unreacted material components 3,microtubes, or microcavities are formed in the centre of the strands, isplaced in the container 1. These cavities in turn may construct a 3Dstructure. Boundary polymerisations (diacid chlorides as material 3,diamines as medium 2) are examples of this. Further variants arepolyclectrolyte complexes (for example Na alginate solutions as material3 and a solution of protonated chitosan as medium 2). Microtube bundlescan be produced by parallel alignment of the metered strands.

[0066] Fifth Embodiment

[0067] In one embodiment, organic and inorganic fillers are present inthe materials used in order to produce three-dimensional objectsconsisting of multiphase polymers and composite materials. For example afilled heat-exchangeable plastic or a hot melt of a nanocompositematerial may be added to water as plot medium from the dispenser 4 by aheated needle.

[0068] In order to achieve higher resolution, better tolerances and morerapid formation processes, alternatively microdispensers with separatelyactuatable multiple nozzles may also be used.

[0069] Sixth Embodiment

[0070] In a further development of the first embodiment, apharmaceutically active material is present in the material 3 releasedby the dispenser 4 (for example fibronectin or growth factors). Sincehigh temperatures are not necessarily required during the process, theprocess may take place, for example at room temperature. Thenpharmaceutically active materials are not decomposed or deactivated andare present in their active form in the three-dimensional object. Theobject may therefore be used, for example as an implant in order topromote cell growth around the implant in the body. Direct processing ofa suspension of living human cells is also possible here. Latticestructures as described in Embodiment 1, thus guarantee the subsequentsupply of cells with nutrient medium (in vitro) or blood (in vitro). Thearrangement shown in FIG. 1 may be sterilised for this purpose (UVlight, ethylene oxide, locating the process in a clean room).

[0071] Gelatine solution, collagen solutions, Na alginate solutions,albumen solutions are thus suitable as excipient material 3 for theliving cells.

[0072] Seventh Embodiment

[0073] In a seventh embodiment, the outlet opening 5 of the dispenser isdesigned as a two-dimensional nozzle panel with in each case singlyactuatable, individually heatable nozzles. This simplifies thelayer-wise formation of a three-dimensional object in that the dispenseris moved only in x direction and not in y direction when using a nozzleseries to form a layer. Furthermore, the use of a nozzle panelfacilitates it being possible to form an object by moving the dispenseronly in the z direction.

[0074] Eighth Embodiment

[0075] In order to keep medium 2 and/or material 3 at a defined distanceor to cause a thermally induced reaction specifically during theplotting process, heating or cooling of the cartridge and pipe formaterial 3, of the bath/building chamber may be carried out using plotmedium 2 or the nozzle(s) separately or in combination.

[0076] Oligourethanes are preferably used as material in the process ofthe invention, because the resulting microstructures, and also thecompositions of the polyuretbanes may be varied in simple manner inorder to control mechanical properties of the resultingthree-dimensional object, which may thus be formed, for example likerubber or very rigidly. Oligourethanes may be used as co-reactivesystem, as described in the third embodiment, or as hot melt analogouslyto the second embodiment.

[0077] The invention facilitates the formation of a plurality ofthree-dimensional structures with different material combinations. Byusing one or more monomers as plot medium, for example a fibrousstructure and/or a backbone structure of a further material may beincorporated in a matrix of the monomer or the monomers and then themonomer or monomers are polymerised.

[0078] In the embodiments described above, maximum resolution of amicrodot or microstrand deposition may currently be achieved usingcommercially available dispensers of about 100 to 200 μm, determined bythe internal diameter of the nozzle, the operating pressure, the movingrate of the nozzle(s) and in particular by the rheological properties ofthe material used.

[0079] Microdot metering may take place with gaps, with coincidence orspirally. Microstrands may be wound spirally using a continuous materialflow, as individual strands, as continuous strands, or metered adaptedto the free form. In addition, liquid material components may be addedto the plot medium as a microjet. A further possibility of meteringconsists in so-called coextrusion, that is in metering a strand having acore and a shell (core/shell strand).

[0080] Rheological properties (flow properties) may be influenced ifadequate material flow and preferably high thixotropy, that is the rapidrise of the viscosity with decreasing shear rates, is to be achieved.Controlled flow after addition of the material is necessary in order toobtain smooth surfaces without causing the collapse or distortion of the3D structure. For example, self-regulating or segmented oligomers may beused in order to control the rheology. For larger three-dimensionalobjects, larger flat nozzles or multiple nozzles may be used, and theflow may be compensated after the addition, for example by appropriateselection of plot medium, in order to obtain smooth surfaces. In orderto control thixotropy, the use of self-regulating nanofillersfacilitates the formation of network structures which react to shearforces.

[0081] The process of the invention does not require thermal or chemicalafter-treatment of the three-dimensional object formed. When selectingappropriate materials, high temperatures do not also have to be setduring the process. This facilitates the use of temperature-sensitive,biologically or pharmaceutically active materials either as additive,such as for example proteins, growth factors and living cells, but alsoas matrix materials, such as for example hyaluronic acid, gelatine,collagen, alginic acid and its salts, chitosan and its salts. Hence, forthe first time biocompatible and biodegradable excipients, which have adefined, freely selectable form and contain thermally andtoxicologically highly sensitive materials or structures, may beproduced in one step. Excipients of this type have considerableimportance for the field of tissue engineering. In particular the novelpossibility of plotting one or more cell types (by means of severalcontainers 4 and several nozzles 5) at spatially precisely definedpoints in a precisely adjustable three-dimensional structure, which alsopermits pores for nutrient supply and removal of metabolic products, isimportant. Organs of mammals consist of a supporting tissue (for examplecollagen) and greatly differing types of cells, which detect verydifferent functions (for example liver cells). Simultaneous in-vitroculture of different cell types creates considerable difficulties, dueto different growth rates and growth conditions. Their simultaneousstructuring to form organs is hitherto only successful for single organs(for example the skin). On the other hand, such a complex structure maybe realised by means of the invention presented here.

[0082] An aqueous solution of calcium ions, thrombin and gelatine (toincrease viscosity) may serve here as an example of medium 2; material 3is then an aqueous solution of human fibrinogen, sodium alginate andliving cells.

[0083] Two mechanisms then lead to gelling: a) complex formation of thealginate to form insoluble calcium alginate and b) gelling of thefibrinogen to form fibrin.

[0084] Here too, both the processability of material 3 may be adjusted,and also an improvement in mechanical properties of the finishedthree-dimensional object may be achieved by adding inorganic or organicfillers.

[0085] The addition of pulverulent hydroxylapatite (main mineral ofmammal bone) may serve here as an example. Hence, a three-dimensionalobject, which may serve to remove bone defects, may be produced inconjunction with living bone cells.

[0086] Likewise, further applications of the invention may lie in thefield of release of active ingredients. The invention facilitates, forexample the production of active ingredient excipients adapted preciselyto the patient; this may serve, for example for the slow release of anactive ingredient—the active ingredient is thus situated in the material3 itself and not on the surface—in the brain, by placing athree-dimensional object adapted to the brain cortex and the activeingredient is released directly in the brain and does not have toovercome the blood-brain barrier. This is important for thepost-operative treatment of brain tumour patients.

[0087] The invention also leads to the advantage that three-dimensionalobjects can be produced individually both for medical applications andfor the production of prototypes in industry and in science.

[0088] In addition, the smallest structures may be formed, since thestructural resolution achieved lies in the range from 150 dpi (170 μm)and can be varied in simple manner, as a function of the internaldiameter of the nozzle(s) used, the operating pressure during addition,the addition rate of the material 3, the moving rate of the nozzle(s),the rheology of plot medium and material and the remaining materialproperties.

[0089] Furthermore, when using multiple nozzles, which are arranged as apanel or matrix, a resolution of 600 dpi or more may be achieved.

[0090] The multiple nozzles are thus constructed as a micromechanicalsystem, in which the individual nozzles are valve-controlled (thenozzles or outlet openings are arranged like a panel or matrix on acommon nozzle plate) and represent in each case an outlet opening to acommon nozzle chamber at its defined panel or matrix position, which issupplied with the material 3 under regulated pressure, comparable withthe “common rail” principle from diesel injection technology).

[0091] The formation of three-dimensional objects in liquid media, thedensities of which are the same or similar, that is somewhatsmaller/larger than the density of the added material and thus serve forbuoyancy compensation of the material 3, or addition to thixotropic orgel-like media, in order to reduce the material flow of the meteredmaterial 3 in the medium 2 to a minimum, makes it possible to have theprojections, undercuts and/or cavities when forming thethree-dimensional objects without operating supporting structures.

[0092] A further advantage of the process of the invention consists init being possible to use a plurality of reactive and non-reactivematerials. For example, co-reactive systems and hot melts having aviscosity which is lower compared to the conventional polymer melts, maybe used.

[0093] The device of the invention and the process of the invention aresuitable not only for biomedical application, but also for the “desktop”construction of three-dimensional objects, which is suitable for anoffice, and for rapid prototyping.

[0094] As is shown in FIG. 4, in a further preferred embodiment of theinvention, a substance (10), which delays the reaction between themedium (2) and the material (3) or their reactive components, is addedeither to the medium (2) or preferably to the material (3). Thissubstance 10 ensures that good adhesion of the material added via thedispenser 4 to already cured structures 30 of material 3, which lie forexample in a preceding plot plane, is achieved. The reaction-delayingsubstance 10 is selected so that the reaction between the reactionpartners 2 and 3 or their reactive ingredients, which takes place mainlyinitially at the boundary between already cured material 30 and addedmaterial 3, is delayed by a time span t (delay time), which issufficient that the added material 3 adheres to the already cured orsolidified structures 30 before it reacts with the medium 2. In theexemplary embodiment shown in FIG. 4, the delay time t is preset by thetime which the material 3 requires in order to flow from one section 30₁, to a section 30 ₂ of an already solidified structure. The delay timelies between about {fraction (1/100)} s and about a few seconds,depending on the materials used and metering rates. Differentsubstances, depending on the co-reactive system of medium 2 and material3 used, are suitable as reaction-delaying substances. Thereaction-delaying substance 10 effects deactivation of the reactingmolecules either of material 3 or of medium 2, in particular those ofmedium 2, which penetrate into material 3 while it is added. After sometime, the molecules of the reaction-delaying substance 10 itself becomeinactive, so that their action is no longer sufficient to prevent thereaction between the material 3 and the medium 2.

[0095] Examples of the reaction-delaying substances are the following:for anionic polyelectrolytes, for example alginic acid, as reactivecomponent in the material 3 and substances having multivalent cations,for example calcium, as reactive component of medium 2, suitablereaction-delaying substances are, for example EDTA, acetylsalicylic acidor heparin, wherein the multivalent cations are masked, or sulphateions, wherein the multivalent cations are precipitated. For cationicpolyelectrolytes, for example chitosan, as reactive component in thematerial 3 and substances having multivalent anions as reactivecomponent of medium 2, suitable reaction-delaying substances are forexample Ca, Ba, or Sr ions, wherein the multivalent anions areprecipitated, or short-chain cationic polyelectrolytes, wherein themultivalent anions are masked.

[0096] For fibrinogen as reactive component of material 3 and thrombinand/or calcium as reactive component of medium 2, anti-coagulants, forexample heparin, are suitable as reaction-delaying substance 10, whereincalcium ions are deactivated and/or thrombin is inhibited.

[0097] For a monomer having a free-radical initiator, for example BPO,as reactive component of material 3 and a coinitiator, for exampleamine, as reactive component of medium 2, a free-radical absorber, suchas a sterically hindered phenol, which destroys resulting free-radicals,is suitable as reaction-delaying substance 10.

[0098] It is understood that the above list is only by way of exampleand that each reaction-delaying substance may be used which leads to adefined reaction delay time for a special co-reactive system of material3 and medium 2. The embodiment described can be used in association withall afore-mentioned embodiments.

[0099] In a further preferred embodiment, reaction-delaying substancesare added as substances which protect the reaction component in material3 or medium 2 from undesirable reactions or prevent such reactions. Forexample, vitamin E (tocopherol) may be used as reaction-delayingsubstance or inhibitor for the case that a thermoplastically processablemeterable polymer is used as material 3 in order to protect it fromoxidation.

[0100] The process described according to all afore-mentionedembodiments is not restricted to the fact that pure materials are usedas material 3 or as medium 2. Mixtures of materials may also be used.For example, blends of polyelectrolytes, fibrinogen, fibrin and othermaterials mentioned are possible as mixtures for the material 3.

[0101] In a further embodiment, it is possible to use a material, whichcontains a material dissolved therein, which precipitates duringtransfer into the medium 2 due to a change in the dissolving propertyand forms a solid structure, as material 3. This embodiment can be used,for example for plotting bone cements based on polymethylmethacrylatesand calcium phosphates for delaying curing. Bone cements are known,which are based on polymerisation of polymethylmethacrylates withphosphates, for example hydroxylapatite, as filler. Solidpolymethylmethacrylate is dissolved in methylmethacrylate, which is amonomer. The resulting highly viscous solution is then mixed with themineral phosphate component. During 3D plotting, a two-component systemof initiator and co-initiator is used. The PMMA/MMA/apatite paste formsthe plot material 3. The initiator is added to the latter, whereinpolymerisation is not yet started by the latter. The co-initiator isadded to the plot medium 2. Polymerisation starts by contact of thePMMA/MMA/apatite paste with the plot medium, which contains theco-initiator. The curing time is thus selected to be as short aspossible. For example, benzene peroxide is used as initiator and anamine as co-initiator.

1. A process for producing a three-dimensional object, comprisingprovision of a non-gaseous medium (2) in a container (1), positioning ofan outlet opening (5) of a three-dimensionally movable dispenser (4) inthe medium (2), discharging of a material (3) consisting of one or morecomponent(s) through the dispenser (4) into the medium (2), wherein thematerial (3) cures after discharge into the medium (2), or leads to theformation of solid structures in contact with the medium (2), and movingthe dispenser (4) to the points which correspond to thethree-dimensional object, to form a solid three-dimensional structure.2. The process according to claim 1, in which the medium (2) is providedin the container (1) at a predetermined filling height and the outletopening (5) of the dispenser is positioned below the filling height ofthe medium (2) in the container (1).
 3. The process according to claim 1or 2, in which the density of the medium (2) is selected to beapproximately the same, insignificantly greater or smaller than thedensity of the material (3).
 4. The process according to one of claims 1to 3, in which microdots are formed with gaps, with coincidence orspirally from the material (3), or one or more microstrands are formed,wherein the microstrand or microstrands are metered individually orcoherently, continuously or portion-wise, spirally wound or linearly,with continuous or discontinuous material flow.
 5. The process accordingto one of claims 1 to 4, in which liquid or pasty components of thematerial (3) are used, which is metered as microdrops or as a microjet.6. The process according to one of claims 1 to 5, in which the material(3) is metered as a strand with a core and a shell.
 7. The processaccording to one of claims 1 to 6, in which precipitation of the medium(2) and/or of the material (3) is executed, or in which controlledprecipitation for forming skins around substructures of thethree-dimensional objects is executed, or in which the medium (2)contains one or more precipitating agents for precipitating the material(3) and the material (3) is precipitated.
 8. The process according toone of claims 1 to 7, in which the material (3) contains co-reactivecomponents which react with one another, and/or the first medium (2)contains a co-reactive component which reacts with one or morecomponents of the material (3).
 9. The process according to claim 8, inwhich interfacial polymerisation, polycondensation orpolyelectrolyte-complex formation is executed.
 10. The process accordingto one of claims 1 to 9, in which by removing the material (3) of thecore of a core/shell strand or by executing interfacial polymerisationand removing the material (3), which has not reacted during interfacialpolymerisation, microcavities or microtubes are formed.
 11. The processaccording to one of claims 1 to 10, in which the first medium (2) isdissolved, bound, melted, cured or adhered by metering the material (3)by the material (3) or with it, or in which the material (3) isdissolved, bound, melted, cured or adhered by metering into the medium(2) by the medium (2) or with it.
 12. The process according to one ofclaims 1 to 11, in which a liquid, gel-like, thixotropic, pasty,pulverulent, granulated or solid material is used as medium (2), and/ora liquid, gel-like, pasty material is used as material (3).
 13. Theprocess according to one of claims 1 to 12, in which the medium (2) isselected from the group which contains water, gelatine, an aqueouspolyamine solution and a mixture thereof, and the material (3) isselected from the group which contains oligomers and polymers which areliquid at room temperature, melts of oligomers and polymers, reactiveoligomers and polymers, monomers, gels, pastes, plastisols, solutions,two-component systems with co-reactive components, dispersions andmixtures thereof, and/or
 14. The process according to claim 13, in whichone or more one-component or two-component silicone rubbers are used forthe material (3) as gel, one or more filled oligomers and polymers withone or more organic and inorganic fillers are used as pastes and one ormore isocyanate/polyamide systems are used as two-component systems withco-reactive components, or one or more oligourethanes are used asmaterial (3).
 15. The process according to one of claims 1 to 14, inwhich inorganic and organic fillers are present in the medium (2) or inthe material (3).
 16. The process according to one of claims 1 to 15, inwhich one or more monomers are used as medium (2), a fibrous structureand/or a backbone structure is incorporated in a matrix of the monomeror the monomers and the monomer or monomers are then polymerised. 17.The process according to one of claims 1 to 16, in which the Theologicalproperties of the medium (2) and of the material (3) are adjusted byusing organic and inorganic nanofillers.
 18. The process according toone of claims 1 to 17, in which biologically active substances arepresent in the first and/or in the second material (2, 3).
 19. Theprocess according to claim 18, in which one or more cell types arereleased at spatially precisely defined points for forming a preciselyadjustable three-dimensional structure.
 20. The process according toclaim 19, in which pores for the nutrient supply and for the removal ofmetabolic products are provided in the three-dimensional structure. 21.The process according to one of claims 1 to 20, characterised in that asubstance (10) delaying a reaction between the medium (2) or one of itsingredients and the material (3) or one of its ingredients is added tothe system consisting of the medium (2) and the material (3).
 22. Theprocess according to claim 21, characterised in that the substance (10)is added to the material (3).
 23. The process according to claim 21 or22, characterised in that by adding the substance (10), a reaction time(t) between the medium (2) or one of its ingredients and the material(3) or one of its ingredients, is delayed by so much that the material(3) adheres to already cured material (3) after release into the medium(2) before it cures or leads to the formation of solid structures.
 24. Adevice for executing the process according to one of the precedingclaims, comprising a container (1) for the medium (2), athree-dimensionally moveable dispenser (4) for releasing the material(3) into the medium (2), wherein the dispenser (4) has an outlet opening(5), which can be positioned below the filling height of the firstmaterial (2) in the container (1).
 25. The device according to claim 24,in which the outlet opening (5) is designed as a one-dimensional nozzleor as a two-dimensional nozzle panel with singly actuatable,individually heatable and/or valve-controlled nozzles. and the dispenser(4) has one or more containers for the components of the material (3).26. The device according to claim 25, which is designed so that themedium (2) and/or the material (3) is held at a defined distance or athermally induced reaction is caused specifically during release, byheating or cooling the container for the components of the material (3),and/or the container (1) and/or the nozzle(s).
 27. Use of biologicallyor pharmaceutically active substances in a process according to one ofclaims 1 to 23 and/or a device according to one of claims 24 to 26 forproducing biomedical or biologically active three-dimensional objects.28. Use according to claim 27, wherein proteins, growth factors andliving cells are used as biologically or pharmaceutically activesubstances, hyaluronic acid, gelatine, collagen, alginic acid and itssalts, chitosan and its salts are used as additives or as matrixmaterial.